When all types of debt are counted up, the average U.S. household with any debt (including mortgages) owes a total of $133,568. That total includes an average of $178,037 in mortgage debt, $27,755 for a car loan and $47,047 in student loan debt, in addition to credit card debt. Not all households have every type of debt; that’s why mortgage debt is higher than the total for any kind of debt.

The data were reported earlier this year by NerdWallet and are based on an online survey conducted in early November 2017 of 2,089 U.S. adults ages 18 and over, including 1,201 people who have ever been in credit card debt.

The average American household with credit card debt pays $904 annually in interest charges. According to the NerdWallet survey, consumers accumulate debt for a number of reasons, including spending above their means, becoming unemployed and paying for essentials that their income doesn’t cover.

The study also noted that median household income has risen by 20% over the past decade while the cost of living has risen by 18% in the same period. But significant expenses have risen faster than income: medical expenses are up 34%, “other” expenses are up 30% and food and beverage expenses are up 22%. Housing expenses have risen 20% as well.

Health care accounted for $12 billion in credit card debt. As many as 27 million Americans pay for medical expenses with a credit card. This costs them an average of $471 a year in interest for out-of-pocket medical spending.

NerdWallet’s calculated total of $931 billion does not include overdraft lines that are commonly cited as part of the total but that the researchers exclude because the charges do not necessarily belong to credit card users.

Americans appear to know why they have piled up so much debt. Some 41% say that spending more than they could afford on unnecessary purchases was a contributing factor to their debt load, and 33% said they were forced to pay with credit for necessities not covered by their income. Non-medical emergencies was cited by 33% as a driver of credit card debt, and 23% said they ran up debt after becoming unemployed.